Mo Cassara didn’t have a job three weeks ago. The veteran assistant at Boston College was relieved of his duties, when head basketball coach Al Skinner and the Eagles decided to part ways.

But as everyone in the metropolitan area can attest to — at least those who have witnessed the vicious coaching carousel that has spun around us for five weeks — things change quickly in this business.

Just ask Cassara.

Hofstra athletic director Jack Hayes, who accepted Tim Welsh’s resignation Monday, moved quickly to find his replacement, promoting Cassara today to head coach. Cassara was brought in by Welsh last month as an assistant.

Welsh was then arrested Friday in Long Island on a DWI charge, spent the night in jail, and was suspended before ultimately resigning.

Cassara spent four seasons at Boston College, after a two-year stint as head coach at Division III Clark University, in Massachusetts. In 2003-04, Cassara was an assistant at Dayton. The Flyers were 24-9 that season and advanced to the NCAA Tournament.

“Mo’s experience in the Atlantic Coast Conference and his basketball pedigree will be great additions to Hofstra, and we look forward to an exciting era of Pride Basketball,” Hayes said. “Mo has quickly gained the trust of our athletes, and we are delighted that he will lead our program.”

During Cassara’s tenure in Chestnut Hill, Boston College posted a 72-57 record and made two NCAA Tournaments.

“We have had the opportunity to see Mo’s dynamic leadership, energy and enthusiasm in action,” Hofstra president Stuart Rabinowitz said. “His experience with college basketball, his passion for the game, and his desire to work with athletes in all facets of their development, will serve our basketball team well.”

Cassara, a native of Canton, N.Y., inherits a team with plenty of upside, one that went 19-15 under former coach Tom Pecora, who left for the same position at Fordham.

Hofstra in March advanced to the second round of the Colonial Athletic Association Tournament. The Pride will return junior guard Charles Jenkins, who was named the league’s Player of the Year.